Fix typos in docs and classes

[bky373]

Changes

• annotation-error-handling.adoc
  • records -> things (Change to a more appropriate value)
• events.adoc
  • ConsumerStartingEvent -> ConsumerStartedEvent (To remove duplicates)
• listener-annotation.adoc
  • ProducerConfig -> ConsumerConfig (Change to a more appropriate value)
  • embeddedKafka.getBrokersAsString() -> "localhost:9092" (It's not necessary)
• sending-messages.adoc
  • failedProducerRecord -> producerRecord (failedProducerRecord property does not exist)
• serdes.adoc
  • contentMessageConverter -> contentTypeConverter (contentMessageConverter does not exist)
  • WHen -> When (typo)
• replytopic/features.adoc
  • fixedBackoff -> fixedBackOff (fixedBackoff does not exist)
  • customBackOff -> customBackoff (customBackOff does not exist)
  • DeadLetterPublishingRecover -> DeadLetterPublishingRecoverer (typo)
• ReplyingKafkaTemplate.java
  • start()ed -> started (typo)
• BackOffValuesGenerator.java
  • checkBackOffPolicyTipe -> checkBackOffPolicyType (typo)
• RetryTopicConfigurer.java
  • fixedBackoff -> fixedBackOff (fixedBackoff does not exist)

This document is truly awesome! It's been incredibly helpful for me to learn Spring Kafka.
I hope this PR is a small way to show my appreciation for all the help I've received.
I'd love to contribute code in the future. Thanks again!

[sobychacko]

@bky373 Thanks for the PR. It looks good. One minor comment. Can you add your name as an author using the @author tag in the three Java classes you modified?

[bky373]

@bky373 Thanks for the PR. It looks good. One minor comment. Can you add your name as an author using the @author tag in the three Java classes you modified?

Sure! I updated the list. Thanks!